• Hip & pelvis
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• 제34권2호
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• pp.115-121
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• 2022

Purpose: The purpose of this study was to evaluate the wear and survival rates of third-generation ceramic heads on a conventional ultra-high molecular weight polyethylene liner. Materials and Methods: A total of 160 hips (147 patients with a mean age of 55.9 years) who underwent total hip arthroplasty using the third-generation ceramic head on a conventional polyethylene liner from March 1998 to August 2003 were reviewed retrospectively. Evaluation of the wear rate for 56 hips (49 patients) followed-up for at least 15 years was performed using the PolyWare program version 8 (Draftware Developers, USA). The Kaplan-Meier survivorship was also evaluated. Results: Linear wear and volumetric wear rates were 0.11±0.47 mm/year and 32.75±24.50 mm³/year, respectively. Nine revisions were performed during the follow-up period because of cup or stem loosening. The Kaplan-Meier survival rate, using cup revision or total revision total hip arthroplasty (THA) as the endpoint of analysis, was 93.7% at 15 years and 73.6% at 20 years. Conclusion: Because all revisions were performed between 15 and 20 years in our study, surgeons should pay greater attention to patients who underwent THA with ceramic-on-polyethylene bearing from 15 years postoperatively. Contemporary alumina ceramic on highly cross-linked polyethylene could certainly be a good alternative bearing couple providing better longevity.

• Journal of Oral Medicine and Pain
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• 제23권4호
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• pp.457-473
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• 1998

This study was performed to investigate the morophological and positional correlation between the upper cervical vertebra, the oral structures and the pharyngeal tissues, and the correlation of these anatomical structures with dental features, such as teeth wear area nad tooth contact status, etc. Seventy patients with temporamandibular disorders and sixty three dental students without any signs and symptoms in head and neck region were selected for this study. All they had natural dentition without any fixed and removable protheses. Teeth wear area and arch width wre measured from the upper dental cast, tooth contact status were observed by T-Scan system$^\textregistered$ and four cephaloradiograpohs were taken from four head postures, namely, natural(NHP), forward(FHP), upward(UHP), and downward head postiure(DHP). 22 cephalometric items were measured on the films and the data were processed with SAS statistical program. The result of this study were as follows : 1. In normal group, angle of cervical vertebra tangent and of between hard and soft palate were broader in female subjects than those in male subjacets, but distance from subocciput to axis, size of soft palate, and pharyngeal space width were larger in male subjects. 2. In normal group with natural head posture, the items correlated each others from the three anatomical regions were distance between first nad second vertebra in posterior part, distance from the lingual surface of lower anterior teeth to anterior surface of soft palate, and distance from the hyoid bone to third vertebra. 3. Three set of items showed significant correlation each other in the four head postures in normal group. First set was the angle between hard and soft palate and the idstance from subocciput to posterior arch of first vertebra, second set was the distance between first and second vertebra in posterior part and the teeth wear area, third set was number and force of tooth contact and length of soft palate and distance from anterior tip of hyoid bone to mandibular plane.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제31회 춘계학술대회
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• pp.24-33
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• 2000

The effect of particulate contamination on friction and wear between a negative-pressure picoslider / tri-pad nanoslider and laser-textured disk was studied. Particles of different concentration were injected at the head-disk interface consisting of disks with various textures and slider types at different speed. Durability increased and coefficient of friction decreased as the disk speed increased in a contaminated environment. Frictional characteristics and durability in the data zone were better for those of the laser-textured zone. It was also found that durability of head-disk interface (HDI)decreased as the particle concentration increased. The interface durability with a picoslider was better than that with a nanoslider at any condition in a contaminated environment. Based on the test results, mechanisms were proposed to explain the reasons why durability with a picoslider was superior to that with a nanoslider.

• Tribology and Lubricants
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• 제16권6호
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• pp.469-476
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• 2000

The effect of particulate contamination on the friction and wear between a negative-pressure picoslider/tri-pad nanoslider and laser-textured disk was studied. Particles of different concentration were injected at the head-disk interface consisting of disks with various textures and slider types at different speed. Durability increased and coefficient of friction decreased as the disk speed increased in a contaminated environment. Frictional characteristics and durability in the data Bone were better than those in the laser-textured zone. It was also found that durability of head-disk interface (HDI) decreased as the particle concentration increased. The interface durability with a picoslider was better than that with a nanoslider at any condition in a contaminated environment. Based on the test results, mechanisms were proposed to explain the reasons why durability with a picoslider was superior to that with a nanoslider.

• Tribology and Lubricants
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• 제17권4호
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• pp.312-320
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• 2001

In magnetic hard disk drives, higher areal recording density requires reduction of head-disk spacing. To overcome the increase of stiction associated with reduction of head-disk spacing, a padder slider, which adds pads to slider's air bearing surface, can be one of the practical solution for sub 20 nm flying height, and even for near contact recording. This study investigated the tribological characteristics of a padder slider. A padder slider took off slowly but showed less friction force than a normal slider. The hot/dry CSS test and drag test indicated that pad wear of a padder slider was negligible. The tribological performance of disk is an important factor to be considered. In particular, less carbon overcoat layer of the disk will result in higher stiction and wear in slider/disk interface. In conclusion, a padder slider shows encouraging tribological performances for practical use in HDD.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 추계학술대회 논문집
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• pp.497-504
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• 1998

The manufacturing processes of the head hardened rails and the principles of the heat treatment for carbon steels are introduced in this paper, To get the good wear resistance of the rail, many kinds of microstructure had been developed for the rail head hardening. One of these is the tempered martensitic structure, which is very hard but brittle because of Quenching-Tempering Process. Another is the fine pearlitic structure by Slack Quenching. Now Banitic structure steels are emerging as a potential new material to replace eutectoid pearlitic steels for rail. The main reason of this change is due to the limitaion of pearlitic microstructure with regard to mechanical properties and wear resistances of railway rails.

• 한국의류산업학회지
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• 제2권5호
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• pp.391-397
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• 2000

The purpose of the present research is to determine, for a sample of female college students, the effects of body-cathexis and importance of ideal body image on satisfaction with ready-to-wear. The sample included 177 female college students aged from 18 to 25. To measure the variables, an instrument was developed based on previous studies. Body-cathexis and importance of meeting the ideal body image were measured for five areas of body parts; head/upper body, lower body, height, weight, and torso. Satisfaction with ready-to-wear includes satisfaction with the fit at pant length, thighs, hips, waist, bust, and neckline, and with the variety in ready-to-wear. Research hypotheses were tested using multiple regression. The results showed that there was a positive impact of body-cathexis for a specific body area on ready-to-wear satisfaction which is related to the body area. The effect of importance of meeting the ideal body image on ready-to-wear clothing was different in regard to different areas of body parts.

• 대한가정학회지
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• 제43권1호
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• pp.105-113
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• 2005

The purpose of this study was to suggest a standard sizing system for college female students' head wears according to their head types. The subjects were 193 college women, of 20 to 25 years-old. The subjects were directly measured anthropometrically and indirectly analyzed photographically. In previous tudy (Lim, 2004), 3 clusters as their head types were categorized. the sizing system, which had frequencies more than $4\%$ was classified 6 cases, 7 cases and 9 cases, respectively, by head 3 types. 3 types of size system, which were 56-28-38, 56-30-38 and 57-28-38(Eds note: which of the measurements are head girth, surface length 1 and surface length 2), which were included in 3 clusters. Although head girths were as the same, head surface length was different in size. On the contrary, head surface length was same, head girth was different. The result will contribute to fitness of head wear fitness of consumer, and the amount of production.

• 대한치과보철학회지
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• 제37권3호
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• pp.328-342
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• 1999

This study was performed to investigate the factors related to tooth wear. For this study, 78 patients with temporomandibular disorders and 76 dental students without any signs and symptoms of temporomandibular disorders were selected as the patients group and as the normal group, respectively. Preferred chewing side, Angle's classification, lateral guidance pattern, head and shoulder posture were observed clinically. Electromyographic activity of anterior temporalis and masseter muscle were recorded with $BioEMG^{(R)}$ and occlusal status were recorded with $T-Scan^{(R)}$. Wear facet area of each tooth was measured from working model of upper arch corresponding to the occlusal status from T-Scan. Wear facet area were measured with planimeter in $mm^2$. Total area were divided into incisal, canine, posterior tooth area. Anterior wearfacet area was incisor area plus canine area, and unilateral area was anterior area plus posterior area. The data collected were analyzed by SAS statistical program and the results of this study were as follows: 1. There was no significant difference between the two groups in total werafacet area, and male subjects showed tendency to have larger area in the normal group but female subjects showed tendency vice versa. 2. There was no significant difference related to preferred chewing side and Angle's classification, however some difference was observed by lateral guidance pattern. Anterior wear facet area in subjects of canine guidance was the largest in the three subgroups. 3. Subjects with head tilting to right side had larger posterior and total area, and subjects with higher shoulder in right side had larger canine and anterior area than any other subgrous. 4. Electromyographic activity of masseter muscle was more correlated with wear facet area than anterior temporalis muscle, and tooth contact number and force were significantly correlated with wear facet area, but the most important factor affecting tooth attrition was age.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1997년도 제26회 추계학술대회
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• pp.100-109
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• 1997

Tappet is the part which consists of valve train system in Over Head Valve type diesel engine. The role of tappet is to open and close the intake/exhaust valve by rotating with cam. There are wear problems like scuffing or pitting in cam/tappet system because of the higher Hertzian contact stress and sliding wear characteristics between cam and tappet. In this paper, to find optimal materials combination in cam/tappet system, wear test and rig test were performed. $Si_3N_4$, chilled cast iron, sintered alloy were selected for tappet materials. As the result of test, it is found that $Si_3N_4$ tappet has the excellent wear properties.